The invention relates to a control member for a piezo-valve, comprising an elongated flexible element, which at one of its two axial ends on opposite longitudinal side faces respectively possesses a sealing element having a sealing face.
A control member of this type is for example disclosed in the European patent publication 0 170 990 A1. Here it is part of a piezo-valve belonging to a vacuum control device, it having an elongated flexible element termed a flexure transducer held at one axial end in a manner fixed in relation to the housing and at its other axial end is provided on mutually opposite longitudinal side faces with a respective sealing element, which is opposite to the port or end of a fluid duct. By the application of a voltage to the flexible element the latter is deformed so that a sealing face provided on one of the two sealing elements is selectively brought into contact with a valve seat surrounding the duct port or end.
In the case of the known piezo-valve the two sealing elements are mounted on the flexible element and probably bonded thereto. This means that inaccuracies in manufacture and assembly will make themselves felt at the two sealing elements and will be cumulative in effect and will mean that the distances between the two sealing faces may vary and this will impair operation of the piezo-valve. Because the displacement of the flexible element occurring in the course of operation is generally extremely small, even small dimensional errors will have a disastrous effect and will f. i. render necessary a complex resetting of the nozzles in relation to the flexible element.
One object of the invention is to provide a control member of the type initially mentioned, which renders possible simple but nevertheless more accurate manufacture.
In order to achieve these and/or other objects appearing from the present specification, claims and drawings, in the present invention the two sealing elements are common components of a sealing body, which possesses a connecting section extending between the two sealing elements and designed integrally with the same, such connecting section extending through an opening in the flexible element, the two sealing elements fitting around an edge section, which delimits the opening, of the flexible element and in the peripheral region of the opening resting against a respectively associated longitudinal side face of the flexible element.
It is in this manner that the two sealing elements are collected together in a common sealing body, the elements being connected together via the connecting section so that there is a set distance between the two sealing faces, which may be established even during the production of the sealing body. In this respect there is also more especially the possibility of treating the sealing body at its sealing faces, as required, mechanically and/or thermally independently of the flexible element and without the material of the flexible element being impaired. Since in the mounted state (owing to the sealing elements overlapping the edge section delimiting the opening) there is a mechanical anchoring of the sealing body on the flexible element, and simple and accurate assembly and fitting becomes possible, it is possible to ensure that the distance present between the two sealing faces is not changed and inaccuracy due to assembly is small. It will be clear that the flexible element will be designed in accordance with the opening, the position or layout of any electrodes necessary for operation being more particularly a factor which facilitates producing the opening.
Further advantageous developments of the invention are defined in the claims.
It would in principle be possible to design the opening in the form of a hole with a complete periphery, into which the sealing body is thrust like a button which more especially in this case should have rubber-like properties. An even simpler design is however one in which the opening, through which the connecting section of the sealing body extends, in the flexible element is open or interrupted at its edge in order to permit plugging in of the sealing body through the interruption in the edge or boundary of the opening. In this respect it is an advantage for reasons of symmetry for the edge interruption of the opening to be on the axially orientated end face of the flexible element.
More particularly in cases in which no adequate, secure attachment can be provided, it is recommended to have an additional adhesive bond between the sealing body and the flexible element.
The dimensions of the connecting section may be so selected that the two sealing elements are braced against the flexible element.
The sealing faces may be provided directly on the respectively associated sealing element so that they constitute an integral component of the sealing body. However as an alternative in this respect a particularly advantageous design is one in which the sealing faces are provided on separate sealing face parts and such sealing face parts are on the integral sealing body. It is then possible for the sealing body to be designed in an optimum fashion as regards its holding function on the flexible element and independently of this to select the best suited material for the sealing faces.
Further advantageous developments and convenient forms of the invention will be understood from the following detailed descriptive disclosure of embodiments thereof in conjunction with the accompanying drawings.